Research News

Coming soon: Oil spill-mapping swarms of drones

By GROVE POTTER

Video

This computer simulation shows how five common drones can be
programmed to work together in a swarm to map a nearly 1
kilometer-wide oil spill in nine minutes.

“Communication is the foundation of any swarm.”

Souma Chowdhury, assistant professor

Department of Mechanical and Aerospace Engineering

Thousands of ants converge to follow the most direct path from
their colony to their food and back; a swarm of inexpensive,
unmanned drones quickly map an offshore oil spill.

What could these events have in common?

Each extremely complex task is accomplished by individuals
following very simple rules. But in the case of the drones, a bit
of nature’s magic must be captured in a mathematical
formula.

“Nature may not proactively use mathematics, nor does it
have foresight. It behaves in ways driven by feedback, implicit
drive for adaptation and a certain degree of apparent
randomness,” says Souma Chowdhury, assistant professor of
mechanical and aerospace engineering, School of Engineering and
Applied Sciences. “But we can look at what kind of
mathematical principles define that behavior. Once we have that, we
can use it to solve very complex problems.”

Chowdhury is pioneering a way to program a team of drones to
quickly map an oil spill. His computational efforts, in a paper that he
co-authored with Zachary Ball and Philip Odonkor, were presented
recently at the American Institute of Aeronautics and
Astronautics’ Science and Technology Forum. The study, titled
“A Swarm-Intelligence Approach to Oil Spill Mapping using
Unmanned Aerial Vehicles,” optimized and simulated a
five-drone swarm that can map a nearly one-kilometer-wide spill in
nine minutes.

To make that work, Chowdhury had to overcome the lack of
communication bandwidth typical of a flying ad hoc network and the
short battery life of off-the-shelf drones.

Following the principles partly inspired by the dynamics of a
flock of birds, Chowdhury devised a method for the drones to
quickly record whether they are over water, oil or the edge of the
spill. In addition, the drones assume the space around the oil they
have spotted is also oil, although that is recorded as less than
certain. This simple information is shared with the other drones in
the swarm, as opposed to sharing actual images or video, which
would require too much bandwidth.

“Communication is the foundation of any swarm,” he
says.

As the drones move from point to point over the spill, they
avoid going over space that other drones already have covered.
Thus, with five drones making observations every five seconds, the
size of the spill can be determined quickly.

The drones also fly to their base, on a boat, when their
batteries get low. The drones that replace them on the search
already have the information from all the other drones, so they
avoid previously mapped locations.

“There is no need for human interaction during its entire
mission,” he says. “That’s the big
deal.”

Another big deal is the cost. Chowdhury’s approach assumes
simple, affordable drones, which makes it accessible to many more
people. “This task can be accomplished by off-the-shelf
drones that cost under $1,000. All they need is to have a simple
drone-mountable camera system and use our software,” he
says.

Collision avoidance is another challenge for the swarm and here,
too, Chowdhury is following nature’s simple rules. In recent
work reported by the University of Queensland, researchers
watched very carefully how parrots never crashed into each other.
They observed through tunnel experiments that they always veer to
the right, a simple rule that keeps every member of the flock
safe.

Chowdhury‘s lab is exploring how using similar principles,
drones can pre-emptively turn a certain angle to the right when
they sense another flying member of the swarm. He is writing that
in a companion paper to be submitted to another international
conference later this year.

Swarming drones could be used elsewhere, such as mapping forest
fires or other natural disasters. It’s possible they could be
used to help locate people trapped after an earthquake by changing
the type of cameras used.